Observing Log for 2007-02-01

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Location: Billingborough (South Lincolnshire, UK)
From: 2007-02-01 14:00 UT
To: 2007-02-01 15:00 UT
Equipment: Solarscope
Canon EOS 400D
Temperature: 11.6C ...
Dew Point: 8.8C ...
Humidity: 83% ...
Wind Speed: Calm ...
Pressure: 1025.6hPa ...

Mostly clear and still day but with some cirrus cloud about. I was about to take the Solarscope out to do a quick sunspot count when I noticed that a faint circumzenithal arc was visible.

Circumzenithal Arc and Sundog

From: 2007-02-01 14:00 UT
To: 2007-02-01 14:30 UT

The circumzenithal arc was rather faint, nowhere near as good or as obvious as the last one I saw. However, I went indoors and got my Canon EOS 400D and tried to take some images. The following image is the best of that bunch. The arc is hard to see, it's in the bottom half of the picture.

Circumzenithal Arc

I then noticed that there was a sundog to the right of the Sun. This was quite bright and had some colour to it.

Sundog to right of Sun

I watched the sundog for a short while as it started to fade. I also noticed that the arc had faded to the point that it was almost impossible to see.


From: 2007-02-01 14:35 UT
To: 2007-02-01 14:40 UT

Now that the display of the circumzenithal arc and sundog had faded I got the solarscope out and did a sunspot count.

Active area 940 was still visible. It still had 1 large spot (that now had an obvious penumbra) but I could also now count 6 small faint spots in a chain close to it.

New active area 941 was visible with 1 dark spot.

Circumzenithal Arc and Sundog Again

From: 2007-02-01 14:43 UT
To: 2007-02-01 15:00 UT

The circumzenithal arc was visible again, still faint, but noticeable. I had a go at taking some more photographs. Again, it's rather hard to see in the image:

Circumzenithal Arc

The following image is the previous one, heavily processed in an attempt to better bring out the arc:

Circumzenithal Arc

I then noticed that a sundog had formed to the left of the Sun. This one was also bright and had a fair bit of colour to it too:

Sundog to the left of Sun

I watched for a short while longer as the arc and the sundog came and went as the clouds moved and then finally returned to my office at around 15:00 UT.

Page last modified: 2013-04-09 09:19:19 UT
Dave Pearson <davep@davep.org>
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